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---
title: Override Class Declarations by Styling ID Attributes
localeTitle: 通过样式ID属性覆盖类声明
---
## 通过样式ID属性覆盖类声明
为了理解CSS中的覆盖首先必须了解CSS中的优先原则。
要记住的关键规则是从底部到顶部读取CSS。
一个例子是:
```html
<style>
body {
background-color: black;
font-family: Arial;
color: black;
}
.red-text {
color: red;
}
.blue-text {
color: blue;
}
</style>
<h1 class="red-text blue-text">Example</h1>
```
在上面的示例中,文本`Example`将为蓝色,因为最后添加的类是`blue-text`
**记住`id`属性优先于类,这意味着它排名最高是关键。**
您可以通过在类的名称前面添加`#`来创建`id`属性,如下所示:
```html
<style>
#purple-text {
color: purple;
}
</style>
```
下面是一个示例,向您展示如何**通过样式ID属性覆盖类声明**
```html
<style>
body {
background-color: black;
font-family: Arial;
color: black;
}
.red-text {
color: red;
}
.blue-text {
color: blue;
}
#green-color {
color: green;
}
</style>
<h1 id="green-color" class="red-text blue-text">Example</h1>
```
这将使文本`Example`为绿色,因为`id`属性将始终优先于`class`声明。